The present invention relates to an electronic apparatus having at least two electronic parts operating at different temperatures, respectively; and, more particularly, to an electronic apparatus employing a cooling structure for cooling at least two electronic parts operating at different cooling temperatures, respectively.
More than two electronic parts or electronic units are usually used in a single electric circuit of an electronic apparatus, e.g., a communications apparatus. Such electronic parts or units of the electronic apparatus can operate at different operating temperatures, respectively, and such being the case, there may exist electronic parts that need to be operated at low or ultra low temperatures.
FIG. 1 shows an electronic apparatus 1 employing a conventional cooling structure for cooling such electronic parts operating at low temperatures. The electronic apparatus 1 includes a thermally insulated vacuum vessel 2 and a cold head 4 disposed therein. The cold head 4 is thermally connected with a cooler 8 via a supporting column 3, which hermetically passes through a lower portion of the thermally insulated vessel 2. The supporting column 3 further serves as a passageway for circulating coolant of the cooler 8 between the cold head 4 and the cooler 8.
Mounted on the cold head 4 are a superconducting filter 10, an isolator 12, and a low noise amplifier 14, which are electrically connected together via a cable 16. One end of the cable 16 is electrically connected to an external electronic apparatus (not shown), e.g., a communications apparatus, via a first connector 18. The other end thereof is coupled to an external antenna 22 via a second connector 20, wherein each of the connectors 18, 20 is of a thermal insulator.
A signal received by the antenna 22 is inputted to the superconducting filter 10 via the second connector 20 and the cable 16 and then passes through the isolator 12 and the low noise amplifier 14 in sequence. The signal is finally transmitted to the external electronic apparatus via the cable 16 and the first connector 18. Herein, the isolator 12 serves to prevent the superconducting filter 10 from being affected by an input impedance of the low noise amplifier 14.
The superconducting filter 10 is a cryogenic module that can withstand a cooling at a cryogenic temperature, e.g., about 60 K or lower. The cooler 8 cools the cold head 4, which is in contact with the superconducting filter 10 at about 60 K, thereby cooling the superconducting filter 10 to an equivalent temperature of about 60 K at which the superconducting filter 10 can properly function. Herein, the isolator 12 and the low noise amplifier 14, which are adjacent to the superconducting filter 10, are also in contact with the cold head 4, having the equivalent cooling temperature of 60 K.
However, such cooling condition may have an adverse effect on a non-cryogenic electronic part, more specifically, an electronic part having a higher warranted operation temperature. Normally, the isolator 12 is usually a non-cryogenic type having a warranted operation temperature of about 200 K. Thus when operated and cooled at a cryogenic temperature, an erroneous operation or even a breakage thereof may occur. Employing a cryogenic isolator, instead of the non-cryogenic type, can avoid the problems mentioned above in the prior art, but the cryogenic isolator bears high cost and, therefore, is rarely used.
Referring to FIG. 2, another exemplary prior art communications apparatus, more specifically, a receiver 11 having a cooling structure will be explained. Like numerals represent like parts in FIGS. 1 and 2 and thus a detailed description thereof will be omitted.
The receiver 11 includes a thermally insulated vacuum vessel 2 and a cold head 4 disposed therein. The cold head 4 is thermally connected with a cooler 8, which is disposed outside of the thermally insulated vessel 2. Mounted on the cold head 4 are a band pass filter 24 and a low noise amplifier 14. The band pass filter 24 serves to select a desired band signal and the low noise amplifier 14 serves to amplify the selected band signal to a desired level.
The band pass filter 24 is usually a superconducting filter having a component made of a superconducting material, preferably, a high temperature superconducting material, such as bismuth (Bi)-based, titanium (Ti)-based, lead (Pb)-based or Yttrium (Y)-based copper oxide. The high temperature superconducting filter (HTSF) is of a micro-stripe type thin film HTSF or a common resonator type thick film HTSF.
The power for the low noise amplifier 14 is supplied from an external power source (not shown) via a power terminal 28. The low noise amplifier 14 is accommodated inside the thermally insulated vessel 2 for the purpose of noise reduction. In such a case, a cryogenic low noise amplifier (CLNA) is preferably used. A Dewar vessel can be advantageously employed as the thermally insulated vessel 2.
The cooler 8 cools the band pass filter 24 at a cryogenic temperature to realize a superconducting state thereof, wherein power is supplied to the cooler 8 via an external power source terminal 26. The cooler 8 is usually a cryocooler, which repeatedly compresses and expands helium gas during a heat exchange cycle so that cryogenic temperatures in the range of 10s of Kelvins can be obtained. In general, a pulse type Sterling cycle cryocooler of a small size is used for the cooler 8.
The cryogenic temperature of the band pass filter 24 and the low noise amplifier 14 provides several advantages in that: a thermal noise thereof can be reduced; an insert loss of the band pass filter 24 can be reduced; and an attenuation characteristic of the band pass filter 24 can be greatly improved. As a result, by using the receiver 11 of FIG. 2, an output signal of a desired carrier-to-noise (C/N) power ratio can be obtained even for a low level input signal.
Such a cryogenic low noise amplifier operable at the cryogenic temperature is costly. To reduce the cost, a non-cryogenic low noise amplifier may be disposed outside the thermally insulated vessel in replacement of the cryogenic low noise amplifier. However, an elongated signal passage between the low noise amplifier and the band pass filter increases loss of signals transmitted therebetween.
It is, therefore, a primary object of the present invention to provide an electronic apparatus employing a cooling structure for cooling at least two electronic parts operating at different temperatures.
In accordance with a preferred embodiment of the present invention, there is provided an electronic apparatus having at least two electronic parts which operate at different temperatures, respectively, including: a thermally insulated vessel having a cooling part therein; a first electronic part disposed inside the vessel; and a second electronic part disposed inside the vessel, wherein the second electronic part is spaced apart from the cooling part while the first electronic part is in direct contact with the cooling part.
In accordance with another preferred embodiment of the present invention, there is provided a receiver including: a thermally insulated vessel; a cold head disposed inside the thermally insulated vessel; a superconducting filter mounted on the cold head; a low noise amplifier disposed inside the thermally insulated vessel, wherein the low noise amplifier is spaced apart from the cold head and electrically connected to the superconducting filter; and a radiation plate attached to the low noise amplifier.